Data storage tape cartridges have been used for decades in the computer, audio and video fields. The data storage tape cartridge continues to be an extremely popular device for recording large volumes of information for subsequent retrieval and use.
A data storage tape cartridge generally consists of an outer shell or housing maintaining at least one tape reel assembly and a length of magnetic storage tape. The storage tape is wrapped about a hub portion of the tape reel assembly and is driven through a defined tape path by a driving system. The housing normally includes a separate cover and a separate base. Together, the cover and base form an opening (or window) at a forward portion thereof permitting access to the storage tape by a read/write head upon insertion of the data storage tape cartridge into the tape drive. This interaction between storage tape and head may take place within the housing (for example, with a mid-tape load design), or the storage tape may be directed away from the housing to an adjacent area where the read/write head is located (for example, with a helical drive design or a leader block design). Where the tape cartridge/drive system is designed to direct the storage tape away from the housing, the data storage tape cartridge normally includes a single tape reel assembly. Alternately, where the tape cartridge/drive system is designed to provide head/storage tape interaction proximate the housing, a two (or dual) tape reel configuration is typically employed.
Regardless of the number of tape reel assemblies associated with a particular data storage tape cartridge, the tape reel assembly itself is generally comprised of three basic components: an upper flange, a lower flange, and a hub. The hub forms a tape winding surface about which the storage tape is wound. The flanges are disposed at opposite ends of the hub, and are spaced apart to accommodate a width of the storage tape. To reduce the likelihood of the storage tape undesirably contacting one of the flanges during a winding operation, the flange-to-flange spacing is selected to be slightly greater than the width of the tape. However, even when the flanges are so spaced, successive layers of wrapped storage tape can eventually cause the tape winding surface to deform radially inwardly, in turn drawing the flanges toward one another. Thus, deformation of the tape winding surface can lead to contact between the storage tape and the flanges. As a point of reference, contact between either flange and an edge of the storage tape will transfer a high frequency lateral movement of the storage tape back to the read/write head, possibly leading to servo-tracking errors. Notably, other tape reel assemblies eliminate the flanges, such that only a hub is provided.
Tape reel assemblies are typically formed from plastic components. Though cost effective, plastic hubs and flanges can deform under compressive forces associated with successive windings of storage tape. Consumers generally prefer storing as much information as possible in one data storage tape cartridge. This consumer preference translates to wrapping more and more storage tape on the tape reel assembly/assemblies. In the case of a single reel data storage tape cartridge, all of the storage tape is by necessity wound about only one reel. The large number of tape windings directly correlates to a large tape winding force. Accordingly, tape reel assemblies, and especially single reel data storage tape cartridges, are vulnerable to deformation of the tape winding surface that can contribute to servo-tracking errors.
Previously, the lateral storage tape displacement identified above was of minimal concern as the servo-track associated with the storage tape was sufficiently sized to account for expected lateral displacement. In general terms, the servo-track provides a baseline by which the read/write head can ascertain a “position” of the storage tape. The servo-track width has previously been sufficient to accommodate the lateral movement associated with a typical number of storage tape windings about the hub. However, evolution of tape cartridge/tape drive technology has resulted in increased storage of data characterized by smaller track widths, including the servo-track width. The reduced-width servo-track has a limited frequency (or lateral displacement) response. Therefore, the above-described winding surface deformation can lead to contact between the flanges and the storage tape creating a lateral displacement well above the bandwidth of the now smaller sized servo-track. This, in turn, contributes to servo-tracking errors. Similar concerns can arise relative to tape reel assemblies maintained within the tape drive itself (such as with a tape drive adapted to operate a single reel cartridge). Tape reel assemblies used within tape drives are commonly referred to as tape drive spools or take-up reels.
Data storage tape cartridges are useful tools suitable for storing vast amounts of information. With increasing speeds of reading/writing and advanced magnetic tape technology, design of the data storage tape cartridge is directed to providing accurate and consistent storage tape positioning. To this end, any deformation of the hub, and particularly to the winding surface, can result in deflection of the tape position creating errors in reading from, and writing to, the storage tape. Therefore, a need exists for a tape reel assembly configured to resist deformation of the hub at the tape winding surface.